Chibuisi G. Alimba

Genotoxicity and cytotoxicity of chromium, copper, manganese and lead, and their mixture in WIL2-NS human B lymphoblastoid cells is enhanced by folate depletion

Heavy metal exposure or dietary deficiency is associated with increased genetic damage, cancer and age-related diseases. Folate (vitamin B9) required for DNA repair and synthesis may increase cellular susceptibility to metal induced genotoxicity. This study investigated the interactive effects of folic acid deficiency and sufficiency on genome instability and cytotoxicity induced by chromium (VI), copper (II), manganese (II), lead (IV), and their mixture (CCMP) in WIL2-NS human B lymphoblastoid cells. WIL2-NS cells were cultured in folic acid deficient (20 nM) and replete (2000 nM) RPMI 1640 medium treated with different concentrations (0.00-1000 μM) of the metals and CCMP for 48 h. Chromosomal damage and cytotoxicity were measured using the Cytokinesis-block Micronucleus Cytome assay. CCMP, Cr, Pb, Cu and Mn induced concentration dependent, increases in cells with chromosome damage (micronuclei, nucleoplasmic bridges, nuclear buds) and necrotic cells and decreased nuclear division index. The metals exhibited different cytotoxic and genotoxic potentials (CCMP>Cr>Pb>Cu>Mn) in both folate deficient and sufficient cells, with the cytogenotoxic effects being greater in folate deficient cells. Significant interaction between the metals and folic acid suggests that folic acid deficiency exacerbated cell proliferation inhibition and genome instability induced by metals. Folate deficiency, increasing metal concentration, and their interactions explained 3-11%, 74-92% and 4-12% of the variance of DNA damage biomarkers. In conclusion, exposure to the tested metals (0.01-1000 μM) increased chromosomal DNA damage in WIL2-NS cells and this was exacerbated by folate deficiency.

Genotoxicity of Titanium Dioxide Nanoparticles using the Mouse Bone Marrow Micronucleus and Sperm Morphology Assays

Titanium dioxide nanoparticles (TiO2-NPs) have recently been of public health and scientific concern due to their widespread use in industrial and household applications. However, there is limited information concerning its in vivo cytogenotoxicity. In this study, the cytogenotoxic effects of TiO2-NPs on the somatic tissue using the mouse bone marrow micronucleus (MN) assay and on reproductive tissue using the mouse sperm morphology assay and testicular histopathology were investigated. Five concentrations of 9.38, 18.75, 37.50, 75.00 and 150.00 mg/kg bwt were administered intraperitoneally at 0.5 mL/mouse to mice for five and ten consecutive days in the MN assay; and for five consecutive days in the sperm morphology assay. Double distilled water and cyclophosphamide (20 mg/kg bwt) served as negative and positive controls, respectively. A significant (p<0.05) increase in MN was observed in bone marrow cells of treated mice at 37.50 mg/kg bwt concentration in the 5-day exposure and at all concentrations in the 10-day exposure. The sperm cells examined 5 and 10 weeks from the first day of exposure showed significant increase (p<0.05) in abnormal sperm cells at tested concentrations. Histopathologically, TiO2-NPs disrupted the normal cellular architecture of testicular tissues in exposed mice; as it caused severe lesions such as congestion of the interstitium oedema, vacuolation and necrosis. These suggest that the bone marrow and testicular cells may be potential targets for TiO2-NPs induced DNA damage and cytotoxicity in mice. This is of public health importance considering increasing exposure to TiO2-NPs in consumer products.

Genotoxicity and mutagenicity of solid waste leachates: A review

Solid waste production is inevitable and its unsanitary disposal in the environment is of public and environmental health concern. Leachate, generated due to the infiltration of water/precipitation through the waste mass and the wastes biodegradation, is a mixture of dissolved organic matter, inorganic macro-components, heavy metals, xenobiotic organic compounds and microorganisms. Several studies have reported the acute toxicity of leachate using different end points, while evidences are accumulating on their potentials to induce genetic damage. In this wise, different short-term in vivo and in vitro bioassays are being utilized in the evaluations of genotoxicity and mutagenicity of leachates; and the possible mechanisms of genetic damage. This paper reviews reports on leachate-induced genetic damage. There is need for a shift from waste disposal to sustainable waste management. Awareness on possible health impacts or consequences of exposure to solid waste should also be created through health education. Keywords : Solid waste leachate, genotoxicity, mutagenicity, environmental pollution African Journal of Biotechnology Vol. 12(27), pp. 4206-4220

Correlation of melanophore index with a battery of functional genomic stress indicators for measurement of environmental stress in aquatic ecosystem

The correlation of primary stress indicator; melanophore index (MI) with set of genomic stress indicators is important for a better understanding of the cellular stress pathway induced by xenobiotics in aquatic species. This study presents a correlation between melanophore index (MI) and genomic stress indicators in Oreochromis mossambicus treated with lead nitrate, phenol and hexachlorocyclohexane (HCH). O. mossambicus was exposed to sub-lethal concentrations of the different LC50 values (96 h) of the tested chemicals at varying exposure periods and the response via genomic stress indicators and scale melanophores were assessed in accordance with standard protocols. Melanophore index decreased significantly (p<0.01) in a time dependent pattern to the tested chemicals. Gene expression showed significant time dependent increase in the expression of heat shock proteins (HSP70 and HSP60). Vitellogenin (Vtg) expression insignificantly altered. Significant increase in the expression of melanin concentrating hormone (MCH) was observed in response to hexachlorocyclohexane (HCH) in the treated fish. The findings demonstrated an inverse relationship between melanophore index and the set of genomic stress indicators.

Hospital waste incinerator bottom ash leachate induced cyto-genotoxicity in Allium cepa and reproductive toxicity in mice

The potentials of hospital incinerator bottom ash leachate (HIBAL) to induce cyto-genotoxicity in Allium cepa and reproductive anomalies in the mouse were investigated. The leachate obtained from simulation of the bottom ash was analyzed for some physico-chemical parameters. The A. cepa, mouse sperm morphology and histopathological tests were carried out at concentrations ranging from 1% to 50% of the leachate sample. In A. cepa, HIBAL caused significant (p < 0.05) inhibition of root growth and induction of chromosomal aberrations. In the animal assays, there was 100% mortality at the 50% concentrations. The leachate caused insignificant (p > 0.05) concentration-dependent induction of various types of sperm morphology. There was accumulation of fluid in the seminiferous tubule lumen and necrosis of stem cells in the testes. These effects were believed to be provoked by the somatic and germ cell genotoxins, particularly the heavy metals in the leachate. Our finding is of environmental and public health significance.

The genotoxicity and systemic toxicity of a pharmaceutical effluent in Wistar rats may involve oxidative stress induction

There is scarcity of information on the possible mechanisms of pharmaceutical effluent induced genotoxicity and systemic toxicity. This study investigated the genotoxicity and systemic toxicity of a pharmaceutical effluent in Wistar rats. Rats were orally treated with 5–50% concentrations of the effluent for 28 days. At post-exposure, blood, liver, kidney and bone marrow cells were examined for alterations in serum biochemical parameters and hematological indices, histopathological lesions and micronucleated polychromatic erythrocytes formation (MNPCE). The effluent caused concentration independent significant (p < 0.05) alterations in aspartate (AST) and alanine (ALT) aminotransferases, superoxide dismutase (SOD), catalase (CAT), malondialdehyde (MDA), total and direct bilirubin and creatinine. There was reduction in red blood count (RBC), hemoglobin concentration (HGB), platelets, percentage hematocrit (HCT), white blood count (WBC) and mean corpuscle hemoglobin (MCH) except mean corpuscle hemoglobin concentration (MCHC), which increased in the treated rats. Histopathological lesions observed in the liver and kidney of the effluent treated rats were thinning of the hepatic cord, kuffer cell hyperplasia, vacuolation of the hepatocytes and renal cells, multifocal inflammatory changes, necrosis and congestion of the renal blood vessels and central vein. MNPCE significantly increase in the bone marrow of the treated rats compared to the negative control. The concentration of some toxic metals and anions in the effluent were above standard permissible limits. These findings showed that the pharmaceutical effluent caused somatic DNA damage and systemic toxicity in rats may involve induction of oxidative stress, suggesting environmental contamination and health risks in wildlife and humans.

Cytogenotoxicity of Abattoir Effluent in Clarias gariepinus (Burchell, 1822) Using Micronucleus Test

The cytogenotoxic potential of abattoir effluent from Bodija, Nigeria, was investigated using micronucleus test in Clarias gariepinus. Fish was exposed to five different concentrations: 0.2, 0.4, 0.8, 1.6, and 3.1% of the effluent for 7, 14, and 28 days. Tap water and 0.02 mL/L of benzene were used as negative and positive controls, respectively. Physicochemical parameters and heavy metals were analyzed in the effluent in accordance with standard methods. After exposure, blood was collected from the treated and control fish and slides were prepared for micronuclei (MN) and nuclear abnormality evaluation in the peripheral erythrocytes. The effluent induced significant ( ) increase in the frequency of MN in a time dependent manner. Similarly, the frequency of total nuclear abnormalities (blebbing, notch, bud, binucleation, and vacuolation) was higher in the exposed fish than the negative control. Electrical conductivity, nitrate, biochemical oxygen demand, chemical oxygen demand, arsenic, and copper analyzed in the effluent may have provoked the observed cytogenetic damage. The findings herein suggest the presence of clastogens and cytotoxins in Bodija abattoir wastewater which are capable of increasing genomic instability in aquatic biota.

White Rot Fungus (Pleurotus pulmonarius) Cultivated on Lead Contaminated Rice Straw Induced Haematotoxicity and Lead Accumulation in Liver and Kidney of Wistar Rats

White rot fungi (Pleurotus species) are edible mushrooms known for their ability to bioaccumulate contaminants including metals from the environment. There is scarcity of information on the toxic effects of the bioaccumulated metals on organisms at higher trophic levels. In this study, we investigated alterations in haematological indices and erythrocyte morphology and lead bioaccumulation potentials in liver and kidney of Wistar rats fed aqueous extract of Pleurotus pulmonarius cultivated on lead (0, 10, 100, 200, 500 and 1000 mg/L) contaminated rice straw substrate. After 8 weeks of cultivation, mushroom did not germinate in the 1000 mg/L Pb contaminated rice straw. 1 g of mushroom harvested from each of the remaining concentrations showed significant (p<0.001) increase in Pb concentration. Rats exposed to 0.5 mL of the contaminated mushroom extracts for 30 days, showed decreased leucocyte, erythrocyte, haematocrit, platelet and haemoglobin concentrations. Abnormal erythrocyte morphologies like acanthocytes, schizocytes and tear drop were significantly higher in the Pb treated mushroom fed rats than the control. The kidney and liver of treated rats showed significant (p<0.05) increase in Pb concentration with higher Pb bioaccumulation factor in the kidney than the liver. Also insignificant decrease in body and organ weight was observed in treated rats than the control. Pb accumulation in P. pulmonarius increased liver and kidney Pb bioaccumulation and induce alterations in haematological indices and erythrocyte morphology in rats. This poses public health threat to humans and other tertiary consumers foraging white rot fungi from metal contaminated sites.